<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<script>
		var r1=/^[0-9]$/;
		var i=1;
		//alert(r1.test(i));
		
		var r2=/^[a-z0-9_-]{3,16}$/
		var s="12";
		//alert(r2.test(s));//false
		
		s="123"
		alert(r2.test(s));//true
	</script>
	<body>
	</body>
</html>
